All ‘dem Bones: Cleaning Oil from Archeological Bone.

The effects of oil spills in terrestrial and marine environments are a growing concern globally, but understanding and mitigating these effects is a top priority at NCPTT.

Bone is a material with which most of us are familiar. Bone is made up of a combination of proteins: minerals like calcium and potassium: and vitamins. Bones are primarily made of “osseous tissue.” Two types of osseous tissue are in bone, compact and spongy. Compact osseous tissue forms the hard, smooth surface that most people imagine when thinking of bone. Spongy osseous tissue is the same material, but softer and fills the hollow interior.

Shell, like bone, acts as protective outer layer or exoskeleton created by a marine organism. The shells you find washed up on the beach are the remains of the organism after it has died. Shells are typically composed of calcite, calcium carbonate and conchiolin.

Many cultures, present and past, have utilized bone and shell for tools, weapons and ornamentation but what happens when these materials come into contact with crude oil? How do we remove the oil? Can we restore these artifacts if they do come into contact with crude oil? And once cleaned how will this affect their future curation?

That is what we here at NCPTT are trying to find out. Using unprovienced archaeological samples, we are experimenting to find the best method for removing oil from artifacts of bone and shell. The initial stages of the study included a thorough literature review, experiment design and selection of surface washing agents and/or surfactants.

Erin White takes color measurements of bone samples before they are treated.

The experiment will start with documenting the physical condition of the samples prior to applying oil. This involves analyzing the color with the Minolta CR 400 Colorimeter, recording the mass, etc. Once the oil is applied, half of the samples will be cleaned. The other half of the will be placed in a QUV artificial weathering chamber, for approximately 800 hours to simulate real world conditions. This will simulate artifacts that have been exposed to oil and allowed to weather over time before cleaning. Once this stage is complete, we will test each of the selected cleaners on the samples. At the end of the study, we hope to have evidence for best method for removing oil from bone and shell artifacts.

Special Thanks to the Charleston Museum for the donation of bone and to the Southeast Archeological Center for the donation of shell for the project.